Field of the Invention
The present invention relates to an image forming apparatus including a cover that covers an apparatus main body of the image forming apparatus.
Description of the Related Art
An image forming apparatus, such as a copying machine, uses components, such as a laser scanner unit, a motor, a solenoid, and a clutch, operating intermittently or constantly during image formation. These components generate some sounds when these components operate. In addition, due to the vibration generated by these components, surrounding components may resonate and generate sounds. Further, the image forming apparatus also generates sounds due to rubbing, buckling, hitting (collision), and the like of sheets when sheets such as recording sheets are conveyed.
Most of the sounds generated in such apparatus operation include many frequency components equal to or less than about 1 kHz, and the operator of the apparatus and those around the apparatus may feel that these are extremely disturbing noises depending on the magnitude of the sound pressure level at that frequency band. Therefore, a countermeasure is taken to reduce the noises by suppressing the noises themselves generated in the apparatus or preventing the noises generated in the apparatus from leaking to the outside of the apparatus. The countermeasure for preventing the sounds from leaking to the outside of the apparatus is usually performed by shielding the sound with an external cover. In general, a resin material is employed as the external cover from the viewpoint of weight reduction and cost reduction.
Under such circumstances, Japanese Patent Laid-Open No. 2002-365985 discloses a technique for achieving sound insulation by adhering a fibrous acoustic material having a sound absorption function in an audible sound frequency region on an inner surface of an external cover enclosing an apparatus main body.
Further, Japanese Patent Laid-Open No. 2012-122236 discloses a technique for achieving sound insulation by increasing the rigidity of a sealed pouch (sound insulation member) by having the sealed pouch (sound insulation member) made of a flexible thin film material sandwiched and supported by a pair of lattice-shaped frame bodies.
However, in the technique of Japanese Patent Laid-Open No. 2002-365985, the external cover becomes thicker since the acoustic material is used. In the technique in Japanese Patent Laid-Open No. 2012-122236, the lattice-shaped frame body is used to fix the sealed pouch (sound insulation member), and therefore, this also increases the thickness and the weight.